Benign neck masses showing restricted diffusion: Is there a histological basis for discordant behavior?

Abstract

Diffusion weighted imaging (DWI) evolved as a complementary tool to morphologic imaging by offering additional functional information about lesions. Although the technique utilizes movement of water molecules to characterize biological tissues in terms of their cellularity, there are other factors related to the histological constitution of lesions which can have a significant bearing on DWI. Benign lesions with atypical histology including presence of lymphoid stroma, inherently increased cellularity or abundant extracellular collagen can impede movement of water molecules similar to malignant tissues and thereby, show restricted diffusion. Knowledge of these atypical entities while interpreting DWI in clinical practice can avoid potential misdiagnosis. This review aims to present an imaging spectrum of such benign neck masses which, owing to their distinct histology, can show discordant behavior on DWI.

Keywords: Diffusion weighted imaging; Benign neck masses; Restricted diffusion

Core tip: Diffusion weighted imaging improves lesion characterization by providing functional information. However, apart from tissue cellularity, histological background of the lesion can significantly influence the diffusion characteristics of the lesion. Consequently, even benign lesions with atypical histology can show restricted diffusion leading to potential errors in diagnosis.